1. Technical Field
The present disclosure relates to a method of driving a light source, a light source device for performing the method, and a display device having the light source device. More particularly, the present disclosure relates to a method of driving a light source for local dimming driving, a light source device performing the method and a display device having the light source device.
2. Discussion of Related Art
Generally, liquid crystal display (LCD) devices have thinner thickness, lighter weight, and lower power consumption than other types of display devices. Thus, LCD devices are being widely used not only for monitors, notebook computers, and cellular phones, but also for wide-screen televisions. An LCD device includes an LCD panel displaying images using the light transmissivity property of a liquid crystal layer, and a backlight assembly providing the LCD panel with light.
The backlight assembly includes a light source that generates light. For example, the light source may be a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL) or a light-emitting diode (LED). The LED is used as a light source for an LCD panel, because the LED has low power consumption and high color reproducibility.
Recently, a local dimming method dividing the LCD panel into a plurality of regions and controlling amounts of light from the backlight based on the gray level of an image displayed in each of the regions has been developed in order to improve the contrast ratio of the image displayed on the LCD device. The local dimming method reduces amounts of light from LEDs by reducing the amount of driving current provided to the LEDs that are located in a region displaying a darker image than other regions. Additionally, the local dimming method increases the amounts of light from the LEDs by increasing the amount of the driving current provided to the LEDs that are located in a region displaying a brighter image than other regions.
As described above, the backlight assembly includes a plurality of LED strings and a multichannel current controller for providing a driving current to the LED strings connected to each other in parallel, wherein LEDs are connected in series in each of the LED strings, using the local dimming method.
The multichannel current controlling circuit generally controls resistance variations among the LED strings so that the driving currents flowing through the LED strings are controlled to be the same. When an LED is shorted in one of the LED strings, the multichannel current controlling circuit consumes an amount of power corresponding to the shorted LED by producing heat in order to maintain the driving current. The shorted LED often damages the multichannel current controlling circuit.